Reverting from OpenWrt to the
wzr1750dhpd-v24sp2-23709c.bin vendor image is safe and easy to do through the LUCI web interface
|Broadcom BCM4708||512MiB||128MiB||4 x LAN + 1 x WAN||1 x USB2.0 + 1 x USB3.0||Yes||Yes|
The WZR-1750DHP model has at least two hardware revisions. Older revisions have a case with screws and tabs that can be easily opened for serial port access. Newer revisions are glued together and cannot be opened without damaging the case.
J14 is the CFE console and Linux console at
ttyS0. It ships with a four-pin header installed and is compatible with PL2303 adapters.
The J14 pinout from the key pin (a white triangle) is:
The positive pin does not require power, but it can keep the SoC running, and it must be disconnected to completely reset the hardware.
As of OpenWrt 15.05 (Chaos Calmer):
As of OpenWrt r47881 (Designated Driver):
The USB error in the dmesg is:
hub 1-0:1.0: USB hub found hub 1-0:1.0: config failed, hub doesn't have any ports! (err -19)
CFE version 126.96.36.199 (r377098) based on BBP 1.0.37 for BCM947XX (32bit,SP,) Build Date: Thu May 8 19:47:46 JST 2014 (firstname.lastname@example.org) Copyright (C) 2000-2008 Broadcom Corporation.
This build does not have a USB driver and can be rescued only through TFTP.
Uploading the openwrt .trx as a firmware upgrade using Buffalo's stock web interface is rejected as invalid firmware. Note that with stock firmware revisions v2.27 (and probably higher), uploads of non-Buffalo firmware and firmware older than v2.27 are blocked by the web interface. If you have a unit shipped with such a firmware, you can manually override this check as documented at https://www.dd-wrt.com/phpBB2/viewtopic.php?p=783040 and summarized here:
One option is to first go through DD-WRT as described nicely at http://kdpeter.blogspot.co.at/2015/03/buffalo-wzr-1750dhp-openwrt.html?m=1 and summarized here (note that the first 2 steps will already by done if you followed the above steps to downgrade from v2.27):
The second option is to go directly through TFTP with uboot. Buffalo routers typically default to address 192.168.11.1, and the WZR-1750DHP uses the same in uboot. Timing is difficult to get right, one option is to start the following on the command line (assuming a Linux host) immediately after plugging in the router (connected to a LAN port):
sudo ip a a 192.168.11.7/24 dev <your ethernet interface>; atftp 192.168.11.1 --verbose -p -l openwrt-bcm53xx-buffalo-wzr-1750dhp-squashfs.trx
* Note: I have not yet managed to make this work on a new WZR-1750DHP running Buffalo firmware v2.27! It seems that this firmware will (currently) no longer support flashing anything non-Buffalo. *
CFE>prompt in the terminal window.
flash -noheadercommand to the nflash1.trx device.
The console transcript on the WZR-1750DHP should look like this:
CFE> ifconfig eth0 -addr=192.168.0.99 Device eth0: hwaddr 00-11-22-33-44-55, ipaddr 192.168.0.99, mask 255.255.255.0 gateway not set, nameserver not set *** command status = 0 CFE> flash -noheader : nflash1.trx Reading ::
Double-check that the nflash1.trx argument is entered exactly correct here and then start the TFTP client…
Reading :: Done. 7733248 bytes read Programming...done. 7733248 bytes written *** command status = 0 CFE> go check_trx: start nflash1.trx check_trx: exit nflash1.trx Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null) Loading: .. 1263056 bytes read Entry at 0x00008000 Closing network. Starting program at 0x00008000 Uncompressing Linux... done, booting the kernel.
The TFTP client transcript should look like this:
$ tftp 192.168.0.99 tftp> verbose Verbose mode on. tftp> mode octet mode set to octet tftp> put openwrt-15.05-bcm53xx-buffalo-wzr-1750dhp-squashfs.trx putting openwrt-15.05-bcm53xx-buffalo-wzr-1750dhp-squashfs.trx to 192.168.0.99:openwrt-15.05-bcm53xx-buffalo-wzr-1750dhp-squashfs.trx [octet] Sent 7733248 bytes in 2.9 seconds [21390263 bit/s]